Oracle XA Data Source

I have a Oracle XA Data Source set up in WAS 5.0. When I try to get a connection through that datasource as following: Context ctx = new InitialContext(); XADataSource ds = (XADataSource) ctx.lookup("jdbc/xads2"); conn = ds.getXAConnection().getConnection(); I got an exception:java.lang.ClassCastException: com.ibm.ws.rsadapter.jdbc.WSJdbcDataSource Anybody knows why? Thanks in advance...